<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title></title>
    <style>
        html *{
            margin: 0;
            padding: 0;
        }

        .parent{

            display: flex;

            flex-wrap: wrap;

            justify-content: center;

        }
        .son{

            flex: 0 1 300px;
            background-color: #fdf6e3;
            min-height: 200px;
            box-sizing: border-box;
            border: 3px solid #9DB783;
            padding: 20px;
            margin: 20px;

        }

    </style>

</head>
<body>
<section class="parent">
    <article class="son">
    </article>
    <article class="son">
    </article>
    <article class="son">
    </article>
    <article class="son">
    </article>
    <article class="son">
    </article>
    <article class="son">
    </article>
    <article class="son">
    </article>
    <article class="son">
    </article>
    <article class="son">
    </article>
    <article class="son">
    </article>
</section>

</body>
</html>